In 57 games at Louisville, Rodriguez batted .279 with three home runs, 26 RBIs and 11 doubles. He played 26 games at third base and 30 games at second base. He played 12 big league games for the Reds last season.

"I feel really good, especially the last month," Rodriguez said via translator Tomas Vera. "Things have started coming how I planned it. I didn't have a good beginning of the season, but lately things have gotten better. The last few days, I've been doing really well."

Another roster move is coming when the Reds need a starting pitcher on Tuesday, but the switch-hitting Rodriguez adds another bat for the bench in the meantime.

"I'm left-handed strong. They [the Cardinals] called up another left-handed reliever [Kevin Siegrist]," Reds manager Dusty Baker said. "When you're facing a team that you really haven't scored on a lot, I'd pick up two bats if I could. … Pollo can hit. That's what he's here for. Hopefully he helps win a game or two in the meantime. He'll probably pinch-hit more than anything."

The Reds have two switch-hitters on the bench in Rodriguez and Derrick Robinson.

Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.